1. Field of the Invention
The present invention relates to a sheet feeding means to be used in a machine for rotating an image on sheets such as an electrophotographic copying machine, and the like, and more particularly to a sheet feeding means of the type in which the sheet feeding is carried out by flapping up the bottom plate of a sheet feeding cassette on which sheets are loaded.
2. Description of the Prior Art
As is popularly known, a typical sheet feeding mechanism of an electrophotographic copying machine and the like has a bottom plate, in a sheet feeding cassette on which recording sheets are loaded. The bottom plate is flapped up toward a sheet feeding roller or the like to bring the upper sheet into contact with the sheet feeding roller, so as to perform the sheet feeding operation.
In the sheet feeding means of this kind, it is required to draw back a bottom plate flapping-up member from the sheet feeding cassette when said sheet feeding cassette is to be inserted in or to be detached from a sheet feeding table. To cope therewith, it is known to provide a manual lever in the sheet feeding table so as to control the posture of the sheet flapping-up member and by which said sheet flapping-up member is drawn back. Alternatively, a cam is provided onto the side surface of the sheet feeding cassette so as to control the posture of a sheet flapping-up member and by which said flapping-member is drawn back temporarily into the sheet feeding table. However, in the structure of the former countermeasure, the manual lever must be operated every time when the sheet feeding cassette is inserted or detached, so that a very awkward operation is compelled. Such a structure is known from Japanese Laid-open Patent Application No. 52-82237. And in the structure in the latter countermeasure, the sheet feeding cassette is affected by a considerable resistance at the time of insertion or detachment, and therefore, there are difficulties in the insertion and detachment of the sheet feeding cassette. There have also been taken such countermeasure in which a cam is provided onto a sheet feeding table as shown in Japanese Laid-open Patent Application No. 55-135033.